Touch panels for large panels are currently being developed. For example, in the case of a touch panel for a large panel of approximately 65 inches, an optical touch panel is the main type used. Such an optical touch panel is disclosed in Patent Document 1 and Patent Document 2, for example.
FIG. 12 is a drawing that shows a configuration of an optical touch panel of Patent Document 1.
As shown in FIG. 12, an optical touch panel 200 has a light-emitting device 210, and a light-receiving device 220. The light-emitting device 210 has light-emitting elements 211, a substrate 212, and a lens L201. The light-emitting elements 211 are disposed in the periphery of a display surface 231 of a display device 230, and are constituted of LEDs or the like. The light-emitting elements 211 are installed on the substrate 212 substantially along one line.
The lens L201 for the light-emitting elements causes infrared light outputted from the light-emitting elements 211 to converge, and is provided between the light-emitting elements 211 and the display surface 231. The light-receiving device 220 has a lens L202 for light-receiving elements, light-receiving elements 221, and a substrate 222. The light-receiving elements 221 are disposed in the periphery of the display surface 231 of the display device 230, and are constituted of phototransistors or the like.
The light-receiving elements 221 are in the periphery of the display surface 231 of the display device 230, and are disposed facing the light-emitting elements 211 through a space 232 in the vicinity of (above or below) the display surface 231 of the display device 230. The light-emitting elements 211 output light, which passes through the lens L201, and the light-receiving elements 221 receive the light.
The infrared light emitted by the light-emitting elements 211 is caused to converge and is amplified by the lens L201, and then reaches the light-receiving elements 221 (phototransistors), which are placed far from the light-emitting elements 211. After the lens L202 causes the infrared light to converge again, the infrared light reaches the light-receiving surfaces of the light-receiving elements 221.
By providing the optical touch panel 200 with lenses L201 and L202 as stated above, a decrease in resolution of the optical touch panel is prevented.
FIG. 13(a) is a perspective view that shows a configuration of an optical touch panel according to Patent Document 2. FIG. 13(b) is a cross-sectional view of FIG. 13(a).
As shown in FIG. 13(a), the optical touch panel of Patent Document 2 is formed integrally with an electro-optical device 300 that has an image display function, and has a coordinate input function on the display surface thereof.
In the center of the electro-optical device 300, a coordinate input region 302, which is a display surface that displays images and that functions as a touch panel surface, is formed.
Light sources 310 and light-emitting side reflective plates 350 are disposed in light-emitting side periphery regions 303, which are in the vicinity of the coordinate input region 302. Light detectors 320 and light-receiving side reflective plates 360 are disposed in light-receiving side periphery regions 304, which are in the vicinity of the coordinate input region 302. The light detectors 320 are provided with a plurality of light-receiving elements, and are formed on an element substrate.
When the light emitted from the light source 310 reaches the light-emitting side reflective plate 350, the light-emitting side reflective plate 350 reflects the light, and the light travels parallel to the substrate surface towards the coordinate input region 302. The light that travels through the space above the coordinate input region 302 is reflected by the light-receiving side reflective plate 360 and reaches the light-receiving elements of the light detector 320.
In the electro-optical device 300, which is configured as stated above, a position indicated by touching the coordinate input region 302 with a finger or an input stylus is received as input data by the light detectors 320.